The present invention relates to an optical disk recording method and an optical disk recording apparatus for enabling recording of data with recording densities differing from a standard specification of an optical disk to be used.
The present invention also relates to an optical disk recording method and apparatus for recording information on optical disks such as CD-R, CD-RW, CD-WO, MD, DVD, etc. More specifically, the present invention concerns an optical disk recording method and apparatus for dividing a recording area into a plurality of recording zones and for recording data in respective recording zones with different linear densities.
A groove called a pre-groove is formed previously during a course of manufacturing recordable optical disks compliant with CD (compact disk) standards such as a CD-R (CD recordable), a CD-RW (CD rewritable), etc. The pre-groove wobbles. The wobbling frequency is FM-modulated according to absolute position information called ATIP (Absolute Time In Pre-groove). In this specification, a “position” may include the meaning of time. During recording, a wobbling signal is extracted from a photodetecting return signal of an optical pickup. The wobbling signal is FM-demodulated to reproduce the ATIP information. The ATIP information is used to detect an absolute position on the disk. Record information (given information to be recorded) is provided with the detected absolute position information corresponding to the ATIP information as a subcode for recording. Each position in a program area records subcode absolute time information having the same content as that of the ATIP information at the corresponding position. During data reproduction, the absolute position information is decoded from the subcode information included in the reproduced information to detect the absolute position on the disk.
A pre-groove is also previously formed during the disk manufacturing process for recordable optical disks compliant with DVD (digital versatile disk) specifications, such as a DVD-R (DVD recordable), a DVD-RW (DVD rewritable), etc. The pre-groove wobbles at a specified wobbling frequency. During the disk manufacturing process, a pre-pit is previously formed on a land between adjacent pre-grooves. Each pre-pit includes absolute position information called ATIP. During recording, a pre-pit signal is extracted from a photodetecting return signal of an optical pickup. The ATIP information is decoded from the pre-pit signal. The ATIP information is used to detect an absolute position on the disk. Record information is provided with absolute position information as a subcode corresponding to the detected absolute position information for recording. Each position in a program area records subcode absolute time information having the same content as that of the ATIP information at the corresponding position. During data reproduction, the absolute position information is decoded from the subcode information included in the reproduced information to detect the absolute position on the disk.
The conventional recording method predetermines the data recording density according to optical disk specifications. The data recording density cannot be changed. Accordingly, there is no way but changing a track pitch or a reference linear speed of the optical disk itself for ensuring high-density recording or low-density high-quality recording. An existing optical disk is incapable of using a data recording density differing from the specification for recording.
Generally, a system for recording data on CD-R and CD-RW disks employs a constant linear density for increasing the data recording capacity. For this purpose, a wobble is used as a control signal for ensuring the constant linear density and is previously overlapped with a track spirally formed from the innermost periphery to the outermost periphery on an optical disk. FIG. 7 is a schematic block diagram showing a configuration of a conventional optical disk recording apparatus under control of the constant linear velocity for performing constant linear density recording. A spindle motor (SPM) 102 rotatively drives an optical disk 101. A wobble signal is read from the optical disk 101 via a pickup 103 and is supplied to a PLL/wobble decoder 104. The PLL/wobble decoder 104 is also supplied with a reference clock (reference CLK) generated in a reference clock generator 106 based on an oscillation output from a quartz oscillator 105. The PLL/wobble decoder 104 controls revolution of a spindle motor 102 via a spindle controller 107 so that the wobble signal or index signal synchronizes with the reference clock. Accordingly, the optical disk 101 is controlled for rotation with the constant linear velocity.
A divider/multiplier 108 divides or multiplies the reference clock with a fixed ratio of D, and generates an EFM clock (EFM-CLK) having a frequency which is D times higher than the reference clock. An EFM/CD encoder 109 encodes data to be recorded into a specified recording format according to the EFM clock. A write strategy circuit 110 generates record data from the encoded data according to the EFM clock. This record data is written on the optical disk 101 with the constant linear density by means of laser irradiation from the pickup 103.
In recent years, recording media such as CD-R, CD-RW, etc. are available at low prices and are becoming the mainstream of recording media along with the widespread use and the improved manufacturing technology of these media. As exemplified by DVD, there is remarkable advancement in developing a laser used for the pickup and other fundamental technologies for data recording and reproduction. By applying an improved fundamental recording technology to inexpensively available media, there is an increasing demand for additional values such as a higher recording density and improved security while maintaining compatibility with the existing standards.